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publications  of 
The  American  Academy  of  Political  and  Social  Science 

No.  620 


Tropical  Diseases  and  Health  in  the 
United  States 


BY 
JOHN  M.  SWAN,  M.D. 

Medical  Director  of  The  Glen  Springs;  Secretary  of  the  American  Society  of  Tropical  Medicine, 

Watkins,  N.  Y. 


Reprinted  from  THE  ANNALS  of  the  American  Academy  of  Political 
and  Social  Science,  March,  1911 


PHILADELPHIA 

The  American  Academy  of  Political  and  Social  Science 


Prke.  25  cents 


The  American  Academy  op  Political  and 
Social  Science. 

The  American  Academy  of  Political  and  Social  Science  was 
formed  In  Philadelphia,  December  14,  1889,  for  the  purpose  of  pro- 
moting the  study  of  political  and  social  problems  of  the  present  day. 

Besides  the  general  fields  of  sociology,  political  science  and  eco- 
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tional and  International  commerce,  corporations,  and  the  various 
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Science, 

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5'w  2- 


TROPICAL  DISEASES  AND  HEALTH  IN  THE  UNITED 

STATES 


By  John  M.  Swan,  M.D., 

^ledical  Director  of  The  Glen  Springs ;   Secretar}'  of  the  American  Society 
of  Tropical  Medicine,  Watkins,  N.  Y. 


Introduction. — Many  of  the  problems  that  demand  solution  at 
the  hands  of  the  sociologist  concern  the  parasites  that  infest  the 
body  politic,  impairing  its  efficiency.  The  physician,  on  the 
other  hand,  particularly  he  who  is  engaged  in  the  solution  of  the 
problems  of  sanitation,  is  concerned  to  a  very  large  extent  with 
the  study  of  the  parasites  that  infest  the  physical  body,  producing 
sickness  and  death. 

Since  the  development  of  modern  bacteriology,  which  saw  its 
beginning  in  about  1870,  the  knowledge  of  the  causes  of  the  acute 
infectious  diseases  of  man  has  had  an  interesting  and  rapid  evolu- 
tion. Following  naturally  the  discovery  of  the  exciting  causes  of 
various  diseases,  the  methods  of  preventing  the  development  of  those 
maladies  were  rapidly  worked  out.  But  it  was  soon  found  that 
some  afifections  that  acted  like  other  acute  infectious  diseases  of 
known  etiology  could  not  be  associated  with  a  discoverable  bac- 
terium in  the  relation  of  cause  and  efifect.  The  discovery  by 
Laveran,  in  1880,  of  the  Plasmodium  malarise  and  the  demonstra- 
tion of  its  animal  characteristics  led  to  fresh  investigations.  These 
studies,  in  turn,  showed  that  some  of  the  acute  infections  were 
due  to  animal  parasites.  The  understanding  of  the  life  history  of 
these  organisms,  however,  has  proved  to  be  a  much  more  com- 
plicated matter  than  the  description  of  the  biological  characters 
of  the  vegetable  parasites. 

It  has  been  found  that  many  of  the  animal  parasites  of  which 
man  is  the  host  cannot  be  transmitted  from  one  individual  directly 
to  another.  The  parasitic  organism  requires  a  developmental  period 
in  an  intermediate  host  before  it  can  be  inoculated  into  another 
individual  there  to  develop  and  produce  disease.  The  parasitic 
form   which   infects   the   intermediate   host    is   usually   different   in 

(.304) 


Tropical  Diseases  and  Health  in  United  States  151 

morphology  from  that  which  produces  the  disease  in  man.  The 
intermediate  hosts  are  usually  insects  or  some  other  animal  low  in 
the  zoological  scale.  These  low  animal  forms  require  warmth, 
moisture,  and  oxygen  for  their  development.  These  three  requisites 
are  also  necessary  for  the  development  of  the  parasites  themselves, 
as  well  as  for  the  growth  of  the  vegetable  parasites,  bacteria,  that 
produce  disease. 

All  of  the  lower  forms  of  life,  whether  animal  or  vegetable, 
flourish  best  in  warm,  moist  climates,  so  that  we  find  some  regions 
of  the  earth  more  unhealthy  than  other  regions,  on  account  of  the 
greater  amount  of  moisture  and  heat  with  the  resulting  profuse 
growth  of  the  lowest  forms  of  life.  In  addition  to  heat  and  moisture, 
the  lower  forms  of  life  require  a  certain  amount  of  food  in  the 
nature  of  decomposing  animal  and  vegetable  material.  This  is 
found  in  abundance  in  hot,  moist  climates,  particularly  when  no 
effort  is  made  to  prevent  the  accumulation  of  such  decomposing 
masses.  Furthermore,  a  hot,  moist  climate  is  debilitating  to  the 
human  organism,  so  that  initiative  and  energy  are  lacking  and  a 
disposition  is  developed  to  let  things  go  as  nature  apparently  means 
that  they  shall  go :  the  spirit  to  improve  conditions  is  lacking.  Con- 
sequently, we  observe  the  establishment  of  a  vicious  circle;  the 
native  is  lacking  in  energy;  he  permits  masses  of  decomposing 
animal  and  vegetable  matter  to  accumulate  in  the  vicinity  of  his 
dwelling;  this  breeds  the  lower  forms  of  life  which  are  able  to 
develop  the  parasites  that  produce  disease ;  these  parasites  infect 
the  dweller  in  their  neighborhood.  Those  inhabitants  that  escape 
death  are  still  further  reduced  in  vitality  and  their  efficiency  is  still 
further  impaired.  Furthermore,  they  are  carriers  of  disease-pro- 
ducing parasites  which  increase  in  number,  until  finally,  the  neigh- 
borhood acquires  an  unenviable  reputation  as  a  pest  hole. 

Climate. — The  climates  of  the  world  are  divided  by  Dr.  C.  Hart 
Merriam  (National  Geographic  Magazine,  1894,  Vol.  VI)  into  the 
Tropical  Zone,  the  Lower  Austral  Zone,  the  Upper  Austral  Zone,  the 
Transitional  Zone,  and  the  Boreal  Zone,  according  to  the  total 
amount  of  heat  present  during  the  year.  In  the  Tropical  Zone 
there  is  26,000°  F.  of  heat  during  a  year,  the  hottest  period  showing 
a  maximum  temperature  of  78.8°  or  over.  In  the  Lower  Austral 
Zone  the  total  heat  amounts  to  18,000°  F.  with  the  hottest  period 
above  78.8°.    In  the  Upper  Austral  Zone  the  total  heat  is  11,500°  F., 

(305) 


152  The  Annals  of  the  American  Academy 

w  ilh  the  hottest  pcn'cKl  below  78.8°  F.  In  the  Transitional  Zone  the 
total  lieat  is  10,000°  F.,  with  the  hottest  period  1)elow  71.6°  F.  In 
the  lloreal  Zone  the  total  heat  for  the  year  is  below  10,000°  F.  and 
the  hottest  period  is  below  64.4°  F. 

The  Tropical  Zone  extends  from  the  Tropic  of  Cancer,  23°  30' 
north  of  the  equator,  to  the  Tropic  of  Capricon,  23°  30'  south  of 
the  equator.  But  north  of  the  Tropic  of  Cancer  and  south  of  the 
Tropic  of  Capricorn  there  is  a  belt,  the  Lower  Austral  Zone,  in 
which  for  a  considerable  part  of  the  year  the  climatic  conditions 
are  similar  to  those  in  the  Tropical  Zone.  In  the  United  States, 
this  zone  includes  all  of  the  Southern  and  Western  states  below  the 
thirty-fifth  parallel  of  north  latitude :  South  Carolina,  Georgia, 
Florida,  Alabama,  Mississippi,  Louisiana,  and  Texas,  and  parts 
of  North  Carolina,  Arkansas,  Indian  Territory,  Oklahoma,  New 
Mexico,  Arizona,  and  California.  It  is  even  probable  that  this  line 
could  be  pushed  as  far  north  as  the  fortieth  parallel.  In  1909,  for 
example,  Philadelphia  had  a  total  amount  of  heat  of  20,153°  F., 
this  is  over  18,000°  F.  During  the  hottest  period  the  thermometer 
registered  above  78.8°  F.  Even  subtracting  the  558  degrees  excess 
temperature  over  the  normal  temperature  for  Philadelphia  in  1909 
the  total  heat  would  be  19,593  degrees,  enough  to  include  Philadel- 
phia, which  is  39°  57'  north  latitude,  in  the  Lower  Austral  Zone. 
In  19 10  the  total  amount  of  heat  was  19,861°  F.,  with  the  hottest 
period  above  78.8°  F.  Similar  studies  would  show  that  many  places 
in  the  L^nited  States  possess  the  necessary  amount  of  temperature 
for  their  inclusion  in  this  zone. 

Requisites  for  the  Development  of  a  Disease  from  the  Tropics. 
In  order,  however,  that  any  disease  shall  develop  in  a  given 
region  of  the  world,  three  essentials,  in  addition  to  a  proper  cli- 
matic condition,  must  be  present :  the  cause  of  the  disease,  the 
proper  transmitting  agent,  and  susceptible  individuals.  Climatic 
features  may  be  suitable,  the  cause  of  the  disease  may  be  present, 
susceptible  individuals  may  reside  in  the  district ;  but  if  the  trans- 
mitting agent  is  absent  the  disease  will  not  develop.  If  now  the 
transmitting  agent  is  suddenly  introduced  into  that  locality  an 
epidemic  of  the  disease  will  result. 

On  the  other  hand,  the  transmitting  agent  may  be  present  and 
susceptible  individuals  may  reside  in  a  locality ;  but  if  individuals 
harboring  the   parasites   be  not  present,   the   disease   will   not   be 

^396) 


Tropical  Diseases  and  Health  in  United  States  153 

found.  If  now  human  hosts  of  the  parasite  come  to  the  region  in 
question  bringing  the  parasites  with  them  an  epidemic  will  follow. 

Relations  of  the  United  States  nHth  the  Tropics. — The  Anglo- 
Saxon  race  has  had  intimate  relations  with  the  tropics  for  over 
three  hundred  ye^ars.  In  1579  Thomas  Stevens  sailed  from  Lisbon 
to  Goa  in  India.  So  far  as  is  known  he  was  the  first  Englishman 
to  visit  that  great  empire.  In  1583  three  London  merchants  started 
overland  for  India.  This  enterprise  was  followed  by  the  endeavor 
of  three  ships  to  make  the  journey  around  the  Cape  of  Good  Hope 
in  1 591.  The  fabulous  wealth  reported  to  be  in  existence  led  to 
the  formation  of  the  British  East  India  Company,  which  was  char- 
tered in  1600,  and  sent  out  its  first  expedition  in  1601.  Ever  since 
then  England  has  had  intimate  relations  with  the  tropics  and  has 
known  at  first  hand  of  the  ravages  of  its  diseases.  That  part  of 
the  Anglo-Saxon  race  which  resides  in  the  Western  Hemisphere 
has  had  a  merely  casual  acquaintance  with  the  tropics  until  the 
occurrence  of  the  Spanish- American  War,  in  1898.  The  acquisi- 
tion of  the  Philippine  Islands,  Puerto  Rico,  and  Guam,  followed 
by  our  intimate  relations  with  Cuba  and  the  undertaking  of  the 
Panama  Car.al  has  brought  the  problems  of  tropical  pathology  and 
tropical  hygiene  strongly  to  our  attention.  We  suddenly  realize 
that  many  of  our  home  ports  are  within  the  limits  of  the  Lower 
Austral  Zone:  Galveston,  28°  18'  N. ;  New  Orleans,  29°  57'  N. ; 
Mobile,  30°  45'  N. ;  Jacksonville,  30°  45'  N. ;  Savannah,  32°  4'  N., 
and  that  the  United  States-Mexican  border  extends  for  a  varying 
distance  north  and  south  of  the  thirtieth  parallel  of  north  lati- 
tude. We  then  find  that  other  of  our  ports  have  a  total  degree  of 
heat  that  would  be  suitable,  for  a  portion  of  the  year  at  least,  for 
the  development  of  diseases  supposed  to  be  peculiar  to  the  tropics, 
provided  all  the  essentials  were  present. 

We  find  424,313  immigrants  landing  on  our  shores  from  tropical 
and  subtropical  countries  in  1907,  and  224,930  immigrants  from  the 
same  regions  in  1908.  Our  soldiers,  our  sailors,  our  missionaries 
and  our  business  men  are  visiting  the  tropics  in  greater  numbers 
with  the  advancing  years.  We  further  find  that  at  home  we  have 
had  for  many  years  a  disease  comrnon  in  the  tropics,  uncinariasis, 
or  hookworm  disease,  probably  imported  from  Africa  with  slaves. 
Tropical  medicine,  consequently,  is  a  matter  of  intimate  concern 
to  the  health  authorities  of  our  country,  and  not  a  mere  academic 

(397) 


154  ^^'^  Aufials  of  the  American  Academy 

question.  The  immigrant  and  the  homecoming  citizen  are  important 
enough  to  require  consideration  in  this  respect,  if  we  had  never 
had  an  epidemic  of  yellow  fever,  of  plague,  or  of  cholera  in  our 
home  territory.  The  prevention  of  an  epidemic  of  imported  disease, 
however,  is  a  comparatively  easy  matter  when  the  cause  is  known, 
and,  at  the  hands  of  the  United  States  Public  Health  and  Marine- 
Hospital  Service  the  introduction  of  epidemics  has  been  and  will 
be  prevented  so  far  as  foreknowledge,  foresight,  and  purisdiction 
can  accomplish  the  result. 

The  Essential  Feature  of  the  Prevention  of  Tropical  Disease. 
— The  one  essential  feature  of  prevention  of  tropical  diseases  is  the 
cleanliness  of  our  seaports,  the  cleanliness  of  our  inhabitants,  the 
cleanliness  of  our  houses.  By  cleanliness  is  meant  the  drainage  of 
mosquito  breeding  marshes  and  streams,  the  prevention  of  the  devel- 
opment of  flies,  and  the  destruction  of  rats  and  mice,  as  well  as 
the  washing  of  bodies,  the  fumigation  of  houses  and  vessels,  the 
sweeping  of  streets,  the  proper  disposition  of  sewage  and  garbage, 
and  the  inspection  of  food  products. 

The  Tropical  Diseases. — The  following  list  of  disorders  may 
be  looked  upon  as  including  the  diseases  indigenous  to  tropical  and 
subtropical  countries  which  can  be  transmitted  to  temperate  climates, 
upper  austral  and  transitional,  provided  the  requisite  conditions 
of  heat,  moisture,  intermediate  hosts,  parasites,  and  susceptible 
population  are  present  in  the  given  locality. 

A.  Disease  due  to  protozoan  (one-celled)  parasites: 

I,  malaria;  2,  hemoglobinuric  fever;  3,  amebiasis;  4,  try- 
panosomiasis; 5,  kala  azar;  6,  spirochetosis:  (a),  re- 
lapsing fever;  (b).  Rocky  Mountain  fever;  (c), 
tabardillo. 

B.  Diseases  due  to  metazoan  (many-celled)  parasites: 

I,  trematode  infection;  2,  cestode  infection;  3  nematode 
infection. 

C.  Diseases  due  to  bacteria: 

I,  plague;  2,  cholera;  3,  dysentery;  4,  Malta  fever;  5, 
leprosy. 

D.  Diseases  of  unknown  etiology: 

I,  yellow  fever;  2,  dengue;  3.  beriberi;  4,  pellagra. 
^398) 


Tropical  Diseases  and  Health  in  United  States  155 

Malaria  is  a  disease  indigenous  to  the  tropics  and  to  subtropical 
countries.  It  is  caused  by  a  genus  of  protozoan  parasites,  known 
as  Plasmodium,  of  which  there  are  at  least  three,  and,  according  to 
some  writers,  more  species.  The  parasite  is  known  to  undergo  a 
cycle  of  development  within  its  human  host,  which  perpetuates 
the  disease  in  the  individual.  While  the  various  steps  in  this  cycle 
are  taking  place  regularly,  a  second  form  of  development  of  the 
parasite  takes  place,  which  results  in  the  production  of  forms  that 
produce  no  symptoms  in  the  human  host ;  but  which  are  capable 
of  infecting  the  intermediate  host.  The  intermediate  host  of  the 
Plasmodium  is  the  female  mosquito  of  the  subfamily  Anophelinse. 
Not  all  species  of  anopheles  mosquitoes  can  become  infected  from 
the  human  host,  but  at  least  seven  have  been  shown  by  actual  experi- 
ment to  be  the  efficient  agents  for  the  transmission  of  the  disease. 
Manson,  however,  gives  a  list  of  thirty-two  species  from  various 
parts  of  the  world  which  are  known  or  suspected  to  be  efficient 
hosts  of  the  Plasmodium.  After  the  parasite  has  passed  through 
its  developmental  stage  in  the  body  of  the  mosquito,  forms  result 
that  can  be  inoculated  into  a  susceptible  human  subject  by  the  bite 
of  the  insect,  and  so  the  disease  is  spread.  No  other  method  of 
transmission  from  man  to  man  is  known. 

Mosquitoes  always  breed  in  water.  Some  species  prefer  clean, 
slowly  running  water ;  others  prefer  stagnant  water ;  still  others 
breed  in  collections  of  water  in  artificial  containers.  The  members 
of  the  subfamily  Anophelinse  prefer,  as  a  rule,  the  clean,  slowly 
running  water  found  at  the  edges  of  streams  and  in  marshes  in 
which  there  is  some  current. 

The  amount  of  sickness  due  to  malaria  in  a  malarial  country 
is  incalculable.  Woldert  (Texas  Medical  Nezvs,  April,  1908)  esti- 
mates that  malaria  causes  the  loss  of  an  equivalent  of  over  five 
million  dollars  a  year  in  the  State  of  Texas  alone.  The  most  effi- 
cient way  to  prevent  the  sickness  and  death  due  to  this  disease  is 
the  destruction  of  the  breeding  places  of  the  intermediate  host  of 
the  parasite.  Marshes  should  be  drained  or  filled  in.  Streams 
should  be  cleaned  of  the  growth  of  grasses,  flags,  and  sedges  which 
are  found  near  the  banks,  delaying  the  currents,  and  providing  by 
their  interlacing  roots  safe  retreats  for  the  mosquito  larvse  from 
their  natural  enemies.  Artificial  collections  of  water  should  be 
destroyed  or  efficiently  screened  so  that  the  adult  female  cannot 

(399) 


156  The  Annals  of  the  Aincrican  Academy 

gain  access  to  them  for  the  purpose  of  depositing  her  eggs.  All 
money  spent  by  the  state  in  this  work  is  well  invested.  The  return 
is  seen  in  the  increased  efficiency  of  the  individual,  in  the  lowered 
death  rate  and  sick  rate,  and,  in  the  case  of  drained  marshes,  in  the 
increase  in  the  area  of  arable  land. 

A  district  in  which  there  is  no  malaria  may  owe  its  freedom 
to  the  absence  of  the  proper  malaria  carrying  mosquito,  to  the 
absence  of  individuals  harboring  that  form  of  the  malarial  para- 
site in  their  blood  which  can  infect  the  mosquito,  or  to  both.  If 
the  proper  mosquitoes  exist  in  a  given  neighborhood,  but  no  infected 
individuals  are  present,  no  malaria  will  be  found ;  but  if  human 
hosts,  apparently  in  perfect  health,  with  the  suitable  form  of  the 
malarial  parasite  in  the  blood  are  brought  to  the  region,  an  epidemic 
of  malaria  will  result.  For  example,  if  a  rural  district  contains 
swamps  or  choked  streams  in  which  anopheles  mosquitoes  are  breed- 
ing, and  a  gang  of  Italian  or  West  Indian  laborers,  many  of  whom 
harbor  malarial  parasites,  are  imported  for  the  purpose  of  some 
public  work  such  as  road  building  or  canal  excavating,  an  epidemic 
of  malaria  will  follow. 

On  the  other  hand,  a  malarial  district  may  be  rendered  almost 
nonmalarial  by  destroying  the  breeding  places  of  the  mosquitoes. 
The  active  work  of  the  Department  of  Sanitation  of  the  Isthmian 
Canal  Commission  in  searching  for  and  destroying  the  breeding 
places  of  mosquitoes  in  the  Canal  Zone,  and  screening  the  quarters 
of  the  employees,  has  resulted  in  the  reduction  of  the  morbidity 
from  malaria  from  821  per  1,000,  in  1906,  to  282  per  1,000  in  1908, 
and  215  per  1,000  in  1909.  The  mortality  was  reduced  from  8.77 
per  1,000  in  1906,  to  1.34  per  1,000  in  1908,  and  i.io  per  1,000  in 
1909.  This  result  can  be  paralleled  in  any  American  community 
by  similar  methods  with  a  relatively  small  outlay  of  money. 

The  Italian  method  of  furnishing  quinine  to  the  inhabitants  for 
prophylactic  purposes  is-  not  nearly  so  efficient ;  nor  is  a  method 
which  relies  on  screening  the  dwellings  of  the  inhabitants  without 
a  campaign  for  the  destruction  of  the  mosquitoes  and  their  breeding 
places. 

liemoglobinuric  fever,  or  blackwater  fever,  is  believed  by 
many  writers  to  be  dependent  upon  previous  malaria.  If  this  be 
so,  the  control  of  the  latter  will  be  attended  by  the  disappearance 
of  the  former  disease.     There  arc   students  of  tropical   problems, 

(400) 


Tropical  Diseases  and  Health  in  United  States  157 

however,  who  believe  that  hemoglobinuric  fever  is  an  independent 
disease.  If  this  be  true  it  should  be  placed  among  the  diseases  of 
unknown  etiology.  Hemoglobinuric  fever  is  present  in  the  Philip- 
pine Islands,  in  the  West  Indies,  in  Central  and  South  America,  in 
the  Canal  Zone,  in  Texas,  and  in  Arkansas,  and  probably  in  other 
parts  of  the  lower  austral  zone  of  the  United  States.  So  far  as 
we  know  at  present  its  deleterious  influence  upon  the  public  health 
is  not  great  and  no  alarm  need  be  felt  for  an  extensive  propagation 
of  cases. 

Amebiasis  is  a  disease  due  to  a  protozoan  parasite,  Entameba 
histolytica,  which  attacks  the  large  intestine  of  man  and  of  the 
lower  animals.  The  infection  manifests  itself  by  attacks  of  dysen- 
tery, and  in  many  of  the  cases,  as  high  as  33  per  cent  in  some 
instances,  it  is  followed  by  abscess  of  the  liver.  The  parasite  is 
apparently  transmitted  from  man  to  man  by  potable  water.  It  is 
possible  that  it  may  be  transmitted  by  green  vegetables,  in  localities 
where  human  feces  is  used  as  a  fertilizer,  as  is  the  custom  in  China 
and  other  Eastern  countries.  Its  spread  may  be  stopped  by  boiling 
the  drinking  water,  by  the  prohibition  of  the  use  of  human  excre- 
ment as  a  fertilizer,  and  by  the  prohibition  of  indiscriminate  defeca- 
tion into  streams  or  other  sources  of  water  supply  for  towns,  vil- 
lages, or  isolated  farm  houses. 

Amebiasis  is  prevalent  in  the  Canal  Zone,  certain  of  the  West 
India  Islands,  some  of  the  Southern  states,  for  example,  Louis- 
iana, Puerto  Rico,  and  the  Philippine  Islands.  Individuals  with 
intestinal  trouble  returnirrg  from  these  countries  should  be  carefully 
studied  for  the  detection  of  these  parasites. 

Trypanosomiasis  is  a  disease  due  to  a  protozoan  parasite, 
Trypanosoma  gambiense.  It  is  at  first  a  febrile  complaint  which 
bears  some  resemblance  in  its  clinical  manifestations  to  malaria ; 
but  in  its  last  stages  it  is  accompanied  by  a  marked  degree  of 
lethargy  and  is  commonly  known  as  sleeping  sickness.  The  parasite 
is  transmitted  from  man  to  man  by  a  dipterous  insect ;  the  Tsetse 
fly,  Glossina  palpalis.  The  disease  is  confined  to  the  valley  of  the 
Congo  River,  the  shores  of  Victoria  Nyanza,  and  other  parts  of 
tropical  Africa.  •  So  far  as  is  known  Glossina  palpalis  does  not 
breed  on  the  American  Continent,  consequently  no  harm  is  to  be 
apprehended  from  this  disease  in  the  United  States,  even  if  an 
infected  individual  should  land  upon  our  shores.     If  Glossina  pal- 

(401) 


158  The  Annals  of  the  American  Academy 

palis  can  be  1)rcd  in  our  own  lower  austral  region,  the  United  States 
Public  Health  and  Marine-Hospital  Service  will  have  to  institute 
active  fumigation  measures  on  all  ships  coming  from  African  ports 
to  our  Gulf  and  South  Atlantic  ports  to  prevent  the  domestication 
of  the  fly. 

Kala  Azar  is  a  disease  due  to  a  protozoan  parasite,  Leishmania 
Donovani.  It  is  found  in  Assam,  Madras  and  Bengal.  The  method 
of  transmission  of  the  parasite  is  not  known,  and  no  danger  is  to 
be  apprehended  from  this  disease.  Dr.  S.  T.  Darling,  however, 
has  observed  a  few  cases  in  the  Canal  Zone  similar  to  Kala  Azar, 
and  has  found  a  parasite  of  similar  appearance  in  the  organs  of  the 
patients  at  necropsy.  This  parasite  has  been  called  Histoplasma 
capsulatum.  The  possibility  of  serious  danger  to  the  public  health 
from  such  a  source  is  remote. 

The  best  known  example  of  spirochetosis  is  the  European 
relapsing  fever,  due  to  an  organism  known  as  Spirocheta  recurrens. 
A  few  imported  cases  have  been  seen  in  this  country  and  small 
epidemics  have  been  recorded  in  New  York  and  in  Philadelphia  in 
past  years.  The  parasite  is  supposed  to  be  transmitted  by  the  bed- 
bug or  the  body  louse.  No  extensive  epidemic  of  this  disease  has 
been  observed  in  this  country  and  its  further  prevention  will  be 
accomplished  by  isolating  imported  cases  and  by  the  disinfection 
of  the  belongings  of  the  patients  for  the  destruction  of  any  vermin 
that  they  may  harbor. 

In  the  Bitter  Root  Valley  of  Wyoming,  and  in  some  other  parts 
of  our  Rocky  Mountain  region  there  is  an  epidemic  disease,  known 
as  Rocky  Mountain  fever,  which  is  known  to  be  transmitted  by 
the  bites  of  certain  ticks,  Dermacentor  occidentalis.  It  is  probable 
that  this  is  a  spirochetosis. 

The  disease  endemic  in  Mexico  known  as  tabardillo,  which 
caused  the  death  of  the  investigator  who  proved  the  transmission 
of  Rocky  Mountain  fever  by  the  bites  of  infected  ticks,  Dr.  H.  T. 
Ricketts,  is  in  all  probability  of  the  same  nature.  The  public  health 
authorities  of  the  states  forming  the  United  States-Mexican  border. 
Texas,  Arizona,  New  Mexico  and  California,  will  have  to  meet 
the  problem  of  the  prevention  of  the  importation  of  this  infection 
into  our  domain  with  the  increased  communication  across  the 
border. 

The  disease  caused  by  metazoan  parasites  are,  as  a  rule,  intes- 

(402) 


Tropical  Diseases  and  Health  in  United  States  159 

tinal  disturbances  due  to  the  presence  of  the  parasites  in  the  alimen- 
tary tract.  There  are  one  or  two  exceptions  to  this  rule,  notably 
the  disease  known  as  schistosomiasis,  in  which  the  parasites  and 
their  eggs  are  found  in  the  blood  vessels  of  the  gastro-intestinal 
canal  or  of  the  genito-urinary  organs,  and  the  disease  known  as 
filariasis,  in  which  the  parasites  are  found  in  the  lymphodes  or  the 
connective  tissue  in  the  various  parts  of  the  body.  In  filariasis  the 
embryos  are  found  in  the  circulating  blood. 

Many  of  these  parasites  gain  entrance  to  the  human  body  with 
food  or  drink,  others  require  development  up  to  a  certain  stage  in 
intermediary  hosts,  still  others  gain  entrance  to  the  human  body 
through  the  skin.  Much  work  remains  to  be  done  on  the  life  his- 
tories of  many  of  these  animals  before  definite  knowledge  of  the 
manner  of  infection  is  to  be  had. 

The  trematodes  are  low  forms  of  the  natural  order  Vermes. 
With  one  exception  they  are  hermaphroditic  organisms  which  infect 
ihe  various  parts  of  the  gastro-intestinal  tract.  One  variety,  which 
is  indigenous  to  the  Philippine  Islands  and  other  far  Eastern 
countries,  is  found  in  the  lungs.  The  parasites  are  not  known 
to  be  indigenous  to  any  part  of  the  United  States  although  it  is  not 
beyond  the  range  of  possibility  that  they  may  be  represented  in 
our  home  territory.  However,  climatic  conditions  are  such  in  our 
lower  austral  zone  that,  provided  suitable  intermediary  hosts  are 
present,  they  may  become  established  in  this  country.  So  far  as 
we  know,  cleanliness  in  personal  habits,  care  in  the  preparation 
of  food,  and  abstention  from  eating  uncooked  fruit  and  vegetables 
are  all  that  is  necessary  to  prevent  the  spread  of  such  infections. 

Schistosomiasis  is  the  disease  produced  by  a  trematode  para- 
site, in  which  the  male  and  female  generative  orgai.!s  are  contained 
in  separate  bodies.  The  disease  is  also  known  as  bilharziasis.  It 
is  common  in  Egypt  and  in  some  other  parts  of  Africa,  and  in  Asia. 
A  form  of  the  disease  has  been  met  with  in  the  West  Indies  and 
in  some  parts  of  Central  and  South  America.  Th.=i  symptoms 
depend  upon  the  location  of  the  parasites  and  their  Ova.  Some- 
times an  inflammation  of  the  bladder  results ;  in  othei*  cases  the 
symptoms  resemble  those  of  dysentery.  A  variety  of  this  i.^fection  is 
met  with  in  China  and  Japan,  one  case  of  which  has  beei'i  imported 
into  this  country. 

The  cestodes  are  the  tapeworms.    Infection  with  the?^  parasites 

(403) 


i6o  TJic  .iitiials  of  the  American  Academy 

is  by  no  means  confined  to  tlie  tropics  or  to  subtropical  countries; 
l)ul  in  both  these  regions  cestode  infection  is  more  common  than 
in  temperate  climates.  Nearly  all  of  these  parasites  depend  for 
their  development  in  man  upon  the  eating-  of  insufficiently  cooked 
meat.  The  inspection  of  our  abattoirs  by  the  officials  of  the  United 
States  Department  of  Agriculture  prevents  the  marketing  of  infected 
meat,  and  is  a  public  health  measure  of  tlie  first  order.  The  proper 
cooking  of  meat  is  further  responsible  for  the  rarity  of  the  occur- 
rence of  these  worms  in  Americans. 

The  nematodes  are  the  round  worms.  Infection  with  one  of 
these  is  fairly  common  even  among  the  children  of  the  better  class. 
Infection  with  the  hookworm,  Necator  americanus,  has  been  shown 
within  the  past  ten  years  to  be  very  common  in  the  Southern  states. 
Trichiniasis,  infection  with  Trichina  spiralis,  is  seen  in  rare  cases. 
Filarial  infections  have  been  reported  in  our  home  territory.  Pre- 
vention of  these  infections  varies  with  the  individual  parasite. 

Ascaris  lumbricoides  infection  is  to  be  prevented  by  teaching 
children  to  be  careful  of  the  things  which  they  put  into  their  mouths. 
\\'e  do  not  know  the  life  history  of  this  parasite,  but  infection 
appears  to  be  the  result  of  taking  the  embryos  or  the  ova  into  the 
digestive  tract. 

Hookworm  disease,  uncinariasis,  is  a  serious  problem  in  our 
Southern  states.  The  embryos  develop  in  moist,  sandy  soil,  and 
gain  entrance  to  the  body  through  the  skin.  The  wet  sand  adheres 
to  the  skin  of  the  legs  and  feet,  and  the  embryos  burrow  into  the 
underlying  tissues  and  finally  reach  the  intestine  by  a  circuitous 
route.  The  disease  has  long  been  known  in  Egypt  and  other  parts 
of  the  tropics  of  the  Eastern  Hemisphere  as  anchylostomiasis.  It 
was  a  serious  public  health  problem  during  the  construction  of  the 
St.  Gothard  Tunnel,  in  1880.  Our  army  medical  men  found  it 
in  Puerto  Rico,  and  subsequently  the  parasites  were  discovered 
in  the  South.  Its  presence  results  in  a  severe  anemia  which  may 
be  fatal.  The  prevention  of  the  extension  of  the  disease  can  be 
accomplished  by  the  prohibition  of  soil  pollution  and  by  educating 
the  people  to  wear  shoes.  In  many  localities  the  inhabitants  arc 
too  poor  to  buy  shoes.  In  such  circumstances  prevention  of  indis- 
criminate soil  pollution  is  first  in  order.  The  amelioration  of  pov- 
erty, on  the  other  hand,  so  that  each  individual  can  obtain  enough 

(404) 


Tropical  Diseases  and  Health  in  United  States  i6i 

compensation  for  his  work  to  be  able  to  buy  shoes  for  his  family 
is  a  question  for  the  political  economist  and  the  tariff  commission. 

It  has  been  found  in  Puerto  Rico  that  in  cases  of  certain  ladies 
of  the  better  class  who  harbored  Necator  americanus,  the  infection 
had  occurred  through  the  skin  of  the  hands  from  working  in  flower 
gardens,  the  soil  of  which  had  been  fertilized  by  human  feces.  It 
has  also  been  suggested  that  uncinariasis  was  one  of  the  causes  of 
the  high  morbidity  and  mortality  among  the  Union  prisoners  in 
Confederate  prisons  from  1861  to  1865,  particularly  in  Andersonville. 

The  Rockefeller  commission  will  undoubtedly  succeed  in  ban- 
ishing this  infection  from  our  Southern  States.  It  must,  however, 
prosecute  a  long  campaign  of  education  before  it  can  improve  the 
sanitary  conditions  in  the  rural  districts  and  inculcate  new  habits 
of  personal  hygiene  in  the  inhabitants. 

In  filariasis  the  adult  parasite  inhabits  the  lymphnodes  and  the 
connective  tissues.  The  embryos  circulate  in  the  peripheral  blood. 
The  presence  of  these  parasites  excites  a  train  of  diseases,  the  best 
known  of  which  is  elephantiasis.  The  disease  is  present  in  certain 
of  the  West  India  Islands.  The  embryos  are  taken  into  the  stomach 
of  a  female  mosquito  and  undergo  a  metamorphosis  in  the  thoracic 
muscle  of  the  insect.  After  the  change  in  the  embryos  is  completed, 
they  migrate  to  the  proboscis  of  the  mosquito  and  are  inoculated 
into  the  new  individual  by  the  bite  of  the  insect. 

Whatever  of  danger  there  may  be  in  the  importation  of  filariasis 
into  the  United  States  is  to  be  obviated  by  a  mosquito  campaign. 
In  this  infection  the  intermediate  host  is  not  only  the  mosquito 
of  the  subfamily  Anophelinse  but  also  certain  species  of  the  sub- 
family Culicinse.  The  culex  mosquito  will  breed  in  any  kind  of 
water,  some  species  developing  in  almost  pure  filth.  Consequently, 
it  is  not  only  necessary  to  drain  marshes  and  to  clean  out  streams, 
but  also  to  dispose  of  all  collections  of  still  or  stagnant  water ;  the 
water  in  flowerpots  in  cemeteries,  in  discarded  tin  cans,  in  broken 
bottles,  drains,  cisterns,  etc.,  has  been  found  swarming  with  culex 
larvse.  The  collections  of  water  in  the  hollow  branches  and  the 
trunks  of  trees,  and  in  the  corollas  of  many  plants,  such  as  the 
pitcher  plant,  have  been  found  to  be  breeding  places  for  these 
insects.  There  is  no  danger  of  the  direct  transmission  of  filarial 
infection  from  man  to  man. 

Of  the  diseases  due  to  bacteria,  plague  is  the  one  of  most 

(405) 


i62  The  .liinals  uf  the  American  Academy 

interest  to  the  American  health  officer.  The  disease  is  due  to  an 
organism  known  as  Bacillus  pestis.  Through  the  work  of  the  Eng- 
lish Plague  Commission,  done  in  Bombay  and  its  environs,  it  has 
been  definitely  established  that  the  disease  is  originally  one  of  rats 
and  mice  and  that  it  is  carried  from  rat  to  rat  by  the  bites  of  infected 
fleas.  After  the  rat  population  of  a  city  has  been  reduced  by 
the  epizootic,  the  fleas,  no  longer  finding  sufficient  animal  food, 
turn  their  endeavors  to  and  become  temporary  ectoparasites  of 
man.  The  epidemic  then  spreads  from  man  to  man  by  the  bites 
of  infected  fleas.  In  a  few  cases,  about  one  per  cent  in  a  large  epi- 
demic, the  disease  exists  in  man  as  a  pneumonia  excited  by  the 
Bacillus  pestis,  and  this  form  of  the  infection  is  transmissible  from 
man  to  man  directly  by  infected  sputum,  which  is  disseminated  by 
coughing,  and  by  soiled  bed  linen  and  personal  linen. 

In  the  prevention  of  an  epidemic  of  plague,  the  destruction 
of  rats  and  mice,  is  the  important  sanitary  problem.  The  isolated 
patient  is  not  dangerous  provided  he  is  not  suffering  from  the 
pneumonic  form  of  the  disease.  Plague  has  been  present  in  San 
Francisco  twice  within  the  past  ten  years.  In  1900  the  business 
men  and  health  officials  of  San  Francisco  and  California  made  a 
serious  blunder  in  denying  the  existence  of  the  disease,  and,  by 
their  attitude,  causing  the  resignation  of  an  officer  of  the  United 
States  Public  Health  and  Marine-Hospital  Service  who  was  emi- 
nently equipped  for  coping  with  the  situation.  As  a  result,  the 
disease  ran  for  a  period  of  two  or  three  years  with  occasional  cases 
reported,  and  the  rat  population  of  San  Francisco  became  gener- 
ally infected  so  that  in  1907  plague  again  appeared  in  that  city. 
This  time,  however,  profiting  by  the  former  error,  the  health  author- 
ities of  California  and  of  San  Francisco  summoned  the  federal 
authorities  to  their  aid  and.  by  placing  the  matter  entirely  in  the 
hands  of  the  latter,  had  the  satisfaction  of  seeing  the  epidemic 
stopped  in  eight  months  Avith  a  total  of  160  cases  and  78  deaths. 
Fifteen  cases  occurred  in  Oakland  and  Seattle  with  10  deaths. 
During  this  period  the  Public  Health  and  Marine-Hospital  men 
were  killing  10,000  rats  a  week,  about  three  per  cent  of  which  were 
found  infected  with  Bacillus  pestis.  The  officers  in  charge  of  the 
work  further  developed  the  fact  that  the  wood  squirrels  about  Oak- 
land were  infected  with  plague,  and  measures  have  been  taken  to 
destroy  these  rodents. 

(406) 


Tropical  Diseases  and  Health  in  United  States  163 

The  destruction  of  rats  in  our  seaports  is  a  problem  that  should 
at  once  receive  attention  from  the  proper  sanitary  authorities.  A. 
ship  coming  from  a  plague  port  with  infected  rats  in  its  hold 
should  be  so  moored  that  these  animals  cannot  get  ashore.  For 
this  purpose  rat  guards  have  been  devised  for  the  purpose  of  pre- 
venting the  rodents  from  leaving  the  vessel  at  night  by  way  of  the 
hawsers,  and  starting  an  epizootic  among  the  rats  on  land.  Once 
started  in  New  York  or  Philadelphia  these  cities  would  pass  through 
an  experience  similar  to  that  of  San  Francisco.  The  rat  population 
is  ready  to  hand,  the  rat  flea  is  ready  with  his  host,  and  the  climatic 
conditions  from  May  to  October  are  suitable. 

No  advantage  except  a  temporary  one,  is  ever  gained  by  deny- 
ing the  exisence  of  an  epidemic  in  any  city.  The  hiding  of  the 
facts  gives  a  chance  for  the  disease  to  gain  headway  and  to  result 
finally  in  a  greater  loss  to  business  and  a  more  appalling  loss  of 
life  than  though  the  disease  were  admitted  to  exist  from  the  begin- 
ning and  proper  prophylactic  measures  immediately  instituted. 

Cholera  is  due  to  the  Bacillus  cholerse.  It  is  a  water-borne  dis- 
ease, the  infected  individual  polluting  the  water  supply  by  improper 
disposition  of  his  feces.  Flies  are  sometimes  responsible  for  epi- 
demics by  first  alighting  on  objects  contaminated  with  the  bacilli 
and  then  alighting  upon  exposed  food  stufifs.  It  is  hardly  to  be 
conceived  that  an  epidemic  of  this  disease  should  start  in  any  of 
our  American  cities.  The  quarantine  officers  are  constantly  on 
the  lookout  for  cases  of  intestinal  disturbance  in  immigrants  from 
parts  in  which  cholera  exists,  as  well  as  in  the  members  of  the 
crews  of  the  vessels. 

In  Mohammedan  countries  many  pilgrims  returning  from 
]\Iecca  bring  holy  water  with  them  from  the  Holy  City.  In  order 
to  give  all  the  faithful  an  opportunity  to  benefit  from  the  water, 
the  contents  of  the  bottle  are  emptied  into  the  well  or  other  source 
of  water  supply  of  the  village  to  which  the  pilgrim  belongs.  Since 
the  holy  water  frequently  contains  cholera  bacilli,  an  epidemic 
results.  With  the  increasing  Mohammedan  population  of  the 
Pacific  coast  this  is  a  problem  that  may  confront  our  health  offi- 
cers in  the  future.  Infection  of  the  individual  is  to  be  prevented 
by  boiling  the  drinking  water,  by  abstaining  from  the  use  of 
uncooked  foods,  and  by  care  in  the  production  of  the  milk  supply. 
The  house  fly  should  not  be  neglected.     The  patient  is  not  dan- 

(407) 


164  J  he  Aiiiials  of  ilic  xlmcricun  .Uddciiiy 

gerous  provided  his  intestinal  and  other  discharg^cs  are  properly 
sterilized  before  being  consigned  to  the  cesspool  or  sewer,  burn- 
ing is  the  most  efficacious  method  of  disposing  of  infected  human 
feces. 

Dysentery,  except  the  amebic  form,  already  referred  to  under 
the  head  of  amebiasis,  is  due  to  Bacillus  dysenteriae.  The  epidemics 
are  of  minor  import,  so  far  as  they  have  occurred  in  our  own  land. 
Tn  the  tropics  and  in  subtropical  countries,  where  the  climate 
is  depressing  and  where  the  poorer  classes  are  more  constantly 
underfed  and  overworked  than  wnth  us,  the  disease  often  assumes 
serious  proportions.  It  is  water-borne  and  requires  the  same  ])re- 
ventive  measures  that  apply  to  cholera.  The  fly  problem  is  impor- 
tant in  its  relation  to  this  infection. 

Malta  fever  is  caused  by  the  Micrococcus  meltensis.  Cases  of 
the  disease  are  found  in  the  Mediterranean  littoral  in  greatest 
numbers.  Cases  have  been  found  in  Cuba  and  Puerto  Rico,  Cen- 
tral and  South  America,  and  it  is  not  beyond  the  range  of  possi- 
bility that  cases  occur  along  the  United  States  shores  of  the  Gulf 
of  Mexico.  In  Malta,  the  disease  is  supposed  to  be  transmitted 
by  drinking  the  milk  of  infected  goats ;  these  animals  supplying 
the  milk  for  the  inhabitants  of  the  island.  The  disease  is  not  very 
severe  and  the  death  rate  is  small,  about  three  per  cent.  It  is  respon- 
sible, however,  for  a  large  amount  of  invalidism.  The  problems 
to  be  solved  in  case  it  should  ever  be  found  in  our  country  are 
entirely  hypothetical. 

The  attitude  of  the  public  toward  leprosy  is  a  blot  upon  our 
civilization.  The  disease  is  caused  by  the  Bacillus  leprae.  It  is  not, 
strictly  speaking,  a  tropical  disease,  Norway  and  Iceland  being 
countries  in  which  it  is  indigenous.  It  is  transmitted  only  by  very 
intimate  personal  contact.  The  patient  is  not  a  danger  to  the 
community  in  which  he  dwells,  unless  it  be  proved  that  the  sus- 
picion, now  entertained,  that  the  organism  is  transmitted  by  the 
bites  of  infected  bedbugs  is  warranted.  Even  then  cleanliness  is 
the  answer  to  the  public  health  question  involved.  The  segrega- 
tion of  lepers  in  colonies  is  advisable  on  account  of  the  repulsive 
nature  of  the  deformities  seen  in  the  advanced  cases :  but  not 
because  there  is  any  fear  of  an  epidemic. 

Leprosy  is  endemic  in  many  Central  and  South  American 
States.     There  is  a  leper  colonv  in  Louisiana.     It  is  common  in 

(408) 


Tropical  Diseases  and  Health  in  United  States  165 

the  Hawaiian  Islands,  in  China,  in  Japan,  and  in  the  Philippine 
Islands.  The  treatment  of  the  unfortunate  victim  of  this  disease 
who  was  discovered  in  a  village  in  Maryland  about  two  years  ago 
is  shameful,  productive  of  no  good  to  the  general  public,  and  an 
insult  to  twentieth  century  knowledge. 

Of  the  diseases  of  unknown  etiology,  yellow  fever  has  been 
our  most  serious  tropical  problem.  The  disease  is  endemic  in  Cuba 
and  in  Brazil  and  has  frequently  been  seen  in  epidemic  outbreaks 
in  our  Southern  states  and  in  Central  and  South  America.  Some 
cases  have  been  seen  on  the  west  coast  of  Africa,  and  epidemics 
have  occurred  in  the  past  in  Philadelphia,  New  York,  and  Baltimore. 

The  work  of  the  Yellow  Fever  Commission  of  the  United 
States  Army  in  Havana,  in  1900,  has  proved  that  the  disease  is 
transmitted  by  the  bite  of  infected  Stegomyia  calopus  mosquitoes. 
The  problem  of  prevention  of  epidemics,  therefore,  resolves  itself 
into  the  destruction  of  Stegomyia  calopus.  This  was  successfully 
demonstated  in  New  Orleans  in  1908.  Stegomyia  calopus  appar- 
ently always  breeds  in  artificial  collections  of  fairly  clean  water. 
Consequently  the  screening  of  cisterns,  wells  and  reservoirs  is  abso- 
lutely necessary.  The  patient  must  be  treated  in  a  ward  or  an 
apartment  screened  from  the  access  of  mosquitoes,  and  the  apart- 
ment from  which  he  was  removed  at  the  onset  of  the  disease  must 
be  fumigated  for  the  purpose  of  killing  what  adult  mosquitoes 
may  be  contained  in  it ;  but  for  no  other  reason.  The  patient  is 
harmless,  except  he  is  bitten  during  the  first  three  or  four  days 
of  his  illness. 

The  American  people  owe  a  debt  of  gratitude  to  Dr.  James 
Carroll,  Dr.  Walter  Reed,  Dr.  Jesse  Lazear,  and  Dr.  Aristides 
Agramonte  which  pensions  and  monuments  can  but  partially  repay. 
It  is  a  parsimonious  congress  indeed  that  will  neglect  the  widows 
of  Dr.  Carroll  and  Dr.  Reed  while  it  corrects  the  military  records 
of  patriotic  deserters. 

Dengue  is  frequently  met  with  in  epidemic  form  in  the  Southern 
United  States  and  in  the  West  Indies.  It  is  a  considerable  factor 
in  morbidity  statistics  in  the  Philippine  Islands.  It  is  met  with  in 
many  tropical  and  subtropical  countries.  It  is  not  dangerous  to  life, 
the  death  rate  being  less  than  one  per  cent,  and  the  fatal  cases 
being  seen  in  individuals  who  were  already  sufifering  from  some 
chronic  complaint  when  attacked  by  dengue.     Our  knowledge  of 

(409) 


i66  The  Aiuials  of  the  American  Academy 

the  transmission  of  dengue  is  due  to  the  work  of  the  United  States 
Army  Board  for  the  study  of  tropical  diseases  as  they  occur  in 
the  PhiHppine  Islands,  Dr.  P.  M.  Ashburn  and  Dr.  Charles  F. 
Craig.  These  investigators,  following  the  methods  pursued  by 
the  Yellow  Fever  Commission  in  Cuba,  have  demonstrated  the 
transmission  of  the  disease  by  the  mosquito  Culex  fatigans.  The 
prevention  of  epidemics  of  dengue  is  a  question  of  mosquito  exter- 
mination. 

Beriberi  is  a  disease  indigenous  to  China,  Japan,  the  Philippine 
Islands,  the  Malay  Peninsula,  and  India.  It  is  characterized  by 
an  acute  febrile  period,  followed  by  dropsy,  and  later,  by  paralysis. 
The  cause  of  the  disease  is  unknown.  The  majority  of  students 
of  tropical  pathology  are  of  the  opinion  that  it  is  the  result  of  the 
consumption  of  spoiled  rice.  Some  few  observers  believe  it  to 
be  dependent  upon  an  unknown  parasite. 

The  presence  of  a  case  of  beriberi  upon  a  vessel  from  an 
Indian,  a  Chinese,  or  a  Japanese  port  is  no  excuse  for  scareheads 
in  the  newspapers.  It  is  perfectly  safe  to  treat  such  a  patient  in 
the  general  wards  of  a  New  York  hospital. 

Conclusion. — It  is  no  part  of  the  intention  of  the  writer  of 
this  paper  to  increase  the  causes  of  uneasiness  of  certain  suscep- 
tible individuals  among  his  countrymen.  The  knowledge  that  cer- 
tain diseases  exist,  that  they  have  well  known  causes,  that  they 
are  disseminated  by  well  understood  agents,  and  that  their  spread 
can  be  prevented  by  well  tried  methods,  should  make  for  peace 
of  mind  rather  than  for  worry.  A  man  who  is  on  his  way  home 
at  night  will  not  fall  into  the  ditch,  provided  he  knows  where  the 
ditch  is.  The  knowledge  of  the  existence  of  an  epidemic  disease 
is  the  most  important  element  of  the  campaign  to  eradicate  the 
disorder. 

The  application  of  the  various  sanitary  methods  referred  to 
in  the  course  of  this  paper  is  of  the  first  importance  wherever  men 
are  gathered  together.  We  are  fairly  well  informed  as  to  the  value 
of  a  noncontaminated  water  supply,  of  a  clean  milk  supply,  of 
clean  streets,  of  proper  garbage  and  sewage  disposition.  All  these 
things  cost  money,  but  we  now  know  that  the  money  is  well  spent. 
Campaigns  of  mosquito  extermination,  of  fly  destruction,  of  rat 
and  mouse  extirpation  will  be  found  to  be  investments  that  will  pay. 

(410) 


Tropical  Diseases  and  Health  in  United  States  167 

In  the  Xobel  Lecture  at  Harvard  on  December  14.  1910,  ex- 
President  Roosevelt   said: 

JNlany  men  have  rendered  high  and  honorable  service  to  the  United 
States  in  connection  with  the  work  of  the  Panama  Canal,  but  by  far  the 
greatest  and  most  important  work  has  been  rendered  by  Colonel  Goethals. 
It  is  to  him  more  than  to  any  other  one  man  that  we  owe  the  successful 
accomplishment  of  one  of  the  great  business  and  engineering  feats  of  all 
the  ages. 

When  it  is  completed,  Colonel  William  C.  Gorgas  will  have 
made  possible  "more  than  any  other  one  man"  the  construction 
of  the  Panama  Canal.  The  Canal  would  have  been  a  French 
achievement,  had  it  not  been  for  yellow  fever  and  malaria.  What- 
ever of  dishonestv  in  affairs  may  have  existed  in  the  French  com- 
pany was  of  small  import  beside  these  two  tropical  diseases. 
Shoulder  straps  have  never  prevented  the  bite  of  a  malaria  carrier, 
nor  of  a  yellow  fever  carrier. 

[Note. — The  author  would  acknowledge  his  indebtedness  to  Mr.  George 
S.  Bliss,  of  the  Philadelphia  office  of  the  United  States  Weather  Bureau, 
for  valuable  help  concerning  the  climatological  data  herein  contained.] 


(411) 


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and  Commercial 
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Child  Labor,  Vols.  I,  II,  ni,  IV  and  V 
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Labor  and  Wages 

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American  Waterways 

Regulation  of  the  Liquor  Traffic 

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Chinese  and  Japanese  in  America 

The  New  South 

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